Carpet of Shadow (5e Spell)

From D&D Wiki

You coat the ground in hard shadows, making the terrain difficult to traverse. Choose terrain equaling four 5 foot squares, each adjacent to at least one other, it now costs double movement to traverse them.

At Higher Levels. When you cast this spell using a spell slot of 2nd or higher add 2 squares to the area of effect and for each spell level.

If you have mastery of the Dark Terrain path, add 2 additional squares.

Note: this is a fanmade update of the Shadowcaster class found in the Tome of magic. I claim no ownership of any of this content. This was made solely because no official content update for the Shadowcaster class has been released by Wizards of the Coast.*